Study: New plaster shows the healing process in wounds

Study: New plaster shows the healing process in wounds

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Does everything heal well? Novel plasters can indicate wound healing
Researchers in Switzerland are currently working on a patch that shows the status of wound healing without having to remove it. In particular, the treatment of chronic wounds could be improved with the new development.

Control the healing process
Even with minor everyday injuries, it is often extremely uncomfortable to change the bandage. It pulls and pinches, and sometimes a scabbed wound starts to bleed again. Some therefore simply wait for the plaster to come off on its own. This is not possible with chronic wounds. Here the healing process must be checked regularly. A novel wound dressing is intended to warn of poor wound healing - without the dressing having to be removed.

Bacteria can colonize when changing dressings
One speaks of chronic wounds if wounds do not heal after several weeks. For example, they can be a result of diabetes or poor circulation.

The treatment is much more complicated than with conventional wounds. As a rule, the wound dressing must be changed regularly, not only for hygienic reasons, but also to examine the wound, take smears and clean it.

This not only irritates the skin unnecessarily; bacteria can also colonize - the risk of infections increases. It would be better if the bandage remained on the skin longer and the nurses could read the condition of the wound from the outside.

Researchers are working on a new wound dressing
There have been many advances in treating such wounds in recent years. A few months ago, researchers from Leipzig and Dresden reported on a newly designed hydrogel that also contributes to better wound healing.

And scientists at the Fraunhofer Institute for Modular Solid State Technologies (EMFT) in Munich developed a patch years ago that controls wound healing.

Scientists from Switzerland are now also working on a new type of wound dressing.

The experts from the Swiss Federal Laboratories for Materials Testing and Research Empa are currently developing a high-tech system together with ETH Zurich, the Center Suisse d'Electronique et de Microtechnique (CSEM) and the University Hospital Zurich to provide nursing staff with relevant data on the condition of a wound , it says in a message.

Luciano Boesel of the Empa "Biomimetic Membranes and Textiles" department, who coordinates the project at Empa, explains: "A smart wound dressing with built-in sensors should one day provide continuous information about the state of the wound healing process - so the dressing does not have to be changed more often than necessary. "

This enables gentler treatment for the patient and means less effort for the nursing staff. In this case, less effort also means less costs: Last year, $ 17 billion was spent worldwide on wound care.

Wound healing in phases
When wounds heal, the body produces specific substances in a complex sequence of different biochemical processes that vary in metabolic parameters. Depending on the phase, the amount of glucose and oxygen increases or decreases, and the pH also changes.

All of these substances can be detected with special sensors. To this end, the experts are developing a fluorescence measuring device that can monitor several parameters at the same time, which should be portable, inexpensive and easy to use.

It is said to allow the pH, glucose and oxygen levels to be kept in mind during wound healing. If the values ​​change, this allows conclusions to be drawn about further biochemical processes of wound healing.

The pH value is particularly useful for chronic wounds. If the wound heals normally, it increases, for example, to a value of 8, then it decreases to a value of 5 to 6. However, if a wound no longer closes and becomes chronic, the pH value oscillates between 7 and 8.

It would therefore be helpful if the nursing staff at the wound dressing could be warned that the value was consistently high. If the bandage does not have to be removed anyway for hygienic reasons, one could still wait at lower pH values.

And how do the sensors work? The idea behind it: If certain substances appear in the wound fluid, “tailor-made” fluorescent sensor molecules react with a physical signal.

They start to fluoresce, and some even change color in the visible or ultraviolet range. Thanks to a color scale, weaker and stronger color changes can be interpreted and derived from how large the amount of the substances released is.

Glowing molecules in UV light
Chemist Guido Panzarasa from the "Biomimetic Membranes and Textiles" department shows in the laboratory how a sample with sensor molecules begins to fluoresce. To do this, he carefully drops a solution with a pH of 7.5 into a bowl.

The change is clearly visible in UV light. If he adds another solution, the luminosity fades again. A look at the vial with the solution confirms that the pH of the second liquid is lower.

The Empa team has designed a molecule that is composed of benzalkonium chloride and pyranine. While benzalkonium chloride is a substance that is also used for common medical soap and works against bacteria, fungi and other microorganisms, pyranine is a dye that can be found in highlighters and fluoresces under UV light.

"This biomarker works very well," says Panzarasa, "best at pH values ​​between 5.5 and 7.5. The colors can be made visible with simple UV lamps, such as those available in the electronics store. ”

The Empa team recently published their results in the trade magazine “Sensors and Actuators B - Chemical”.

The “designer molecule” has another advantage: thanks to the benzalkonium chloride, it has an antimicrobial effect on the skin. Undesired bacteria could therefore be combated in the future by choosing the right dressing material.

However, further evaluations, such as compatibility with cells and tissues, are still lacking. The researchers therefore do not know how their sensor works in a complex wound.

Monitor the wound on the smartphone
To illustrate what a smart wound dressing could look like in the future, Boesel places a prototype on the laboratory table.

“The entire area on wound dressings does not have to be equipped with sensors. It is sufficient if a few small cylinders are impregnated with the pyranine-benzalkonium molecule and inserted into the carrier material. That doesn't make industrial wound dressings much more expensive than they are now. They become at most one sixth to one fifth more expensive, ”explains Boesel.

When Panzarasa drops various liquids with different pH values ​​onto all the small cylinders of the wound pad prototype, you can clearly see the lighter and darker glowing dots as soon as he turns on the UV lamp.

They can even be seen with the naked eye. It glows bright yellow when liquids with a high pH value come into contact with the sensor. The scientists are certain that since the pH value can be read out so easily and provides precise information about the acidic or basic state of the sample, such a wound dressing is well suited as a diagnostic tool.

The fluorescence meter can be used to achieve more accurate quantitative measurements of pH for medical purposes.

In the future, the signals could also be read out with the help of a smartphone camera, says Boesel. Combined with a simple app, nursing staff and doctors would have a tool with which they could easily read the wound status "from the outside" even without a UV lamp.

Patients would then also have the opportunity at home to recognize an emerging chronic wound early on. (ad)

Author and source information

Video: Advanced Wound Care (May 2022).